Thermochromic ink is widely available in industrial markets. Thermochromic ink has pigments that change color when subjected to a known temperature range. In a first state with first conditions, the thermochromic ink can be used to write on paper. In a second state, under second conditions, the thermochromic ink changes color. Pens with thermochromic ink, such as FriXion pens manufactured by the Pilot Pen Company turn clear when exposed to temperatures above 140 degrees Fahrenheit. Thermochromic ink pens are designed to be erasable in the following way: the person using the pen writes on the page with the thermochromic ink pen. Then the person rubs the writing with the rubber eraser, which creates friction, generating heat above 140 degrees Fahrenheit, and which turns the ink clear. Erasing a whole sheet of paper, several sheets of paper, or a whole notebook by hand would be tedious and would require too much time and effort to be a practical solution.